Anticavitation device for removing boiling liquids from steam and water drums



Oct. 14, 1952 R. F. M. WAESELYNCK 2,513,655

ANTICAVITATION DEVICE FOR REMOVING BOILING LIQUIDS FROM STEAM AND WATERDRUMS Filed Oct. 25,1945 2 SHEETS-SHEET 2 INVENTOR Patented Oct. 14,1952 ANTICAVITATION DEVICE FOR REMOVING BOILING LIQUIDS FROM STEAM ANDWATER DRUMS Raymond Francois Maurice -Waeselynck, Indret, parBasse-Indrc, France, assignor of one-half to Socicte Rateau (SocieteAnonyme), Paris, France, a company of France Application October 23,1945, Serial No. 624,037

In France April 13, 1943 Section 1, Public Law 690, August 8, 1946Patent expires April 13, 1963 4 Claims. 1

When the liquid and gaseous phases of a substance are in equlibriuminside a container, any lowering of pressure at a point inside theliquid which is not overcome by the head of liquid above thecorresponding point, causes the appearance of the pnenomenon ofcavitation. The latter is apparent in particular at the inlet ofdowncomers in steam boilers, and the bubbles of steam which aregenerated, accumulated in the vicinity of said inlet or driven b theliquid flowing to said inlet oppose the downward movement of the waterin circulation.

The above phenomenon is amplified, and its consequences aggravated:

Firstly, if the liquid is already emulsified before arriving in thevicinity of the downcomer inlet, that is to say if it is mixed with asubstantial quantity of steam bubbles;

Secondly, if the downcomer inlet is disposed in such a way that theliquid penetrates into it with a downward movement, and if said inlet isimmersed to a sufiiciently small extent for the vertical movements whichtake place in the vicinity of said inlet to extend up to the surface ofthe liquid. Inv this latter case cavitation starts at the surface of theliquid and extends spontaneously to the whole central zone of thevortices, thus creating a direct communicating chimney between thegaseous phase in the boiler and the downcomer and causing the completefailure of the latter.

The occurrence of these cavitation phenomena,

in a steam boiler, for example, prevents normal circulations of thewater from being established and may be the cause of serious damage.

It is the object of the present application to provide a simple remedyfor these disadvantages, this remedy being applicable, moreover, notonly to downcomers of steam boilers, whether the boilers are to bemanufactured or are already in service, but also to tubings conductinany kind of liquid out of a reservoir where this liquid is to be foundnear its boiling point.

According to this invention, I provide upstream with respect to theusual inlet port of the downcomer a suction chamber the inlet to whichis entirely submerged in the liquid and the top part of which is cooledby any suitable means (injection of cold liquid, surface refrigeration,etc): The inlet aperture of the chamber has a large cross-sectiondisposed in such a way that the liquid before entering it has nosubstantial vertical velocity which is likely to start surface VOI''tical movements. Shortly after its admission into the chamber thevelocity of the liquid should 2 be at first ascendent or horizontal insuch a way as to facilitate the discharge of steam bubbles or gasbubbles towards the top part of the chamber which thus forms a steamtrap where these bubbles are condensed as they arrive. The liquid thusdeemulsified and slightly cooled then moves downwards towards the portof the discharge piping.

The chamber may be completely submersed in the liquid or its top partmay partiallyemerge in such a Way as to form a syphon. Its inlet openingis generally, but not necessarily, at a lower level than that of theaxis of: the discharge port. In the case of a discharge pipe of smalldiameter the chamber may be constituted simply by a plunger tube whichprolongs the outlet tube to the interior of the boiler; this plungertube is flared at the inlet and has a high point or steam trap where therefrigeration which produces the condensation is carried out. If thedischarge pipe is of large diameter the chamber may be constructed bymeans of a partition at its top section.

The following description with reference to the appended drawings givensolely by way of examples will show how my invention may be carried out.

Fig. 1 is a sectional elevation on line II of Figure 2, the middle partof the drum being omitted.

Fig. 2 is a horizontal section on Figure 1.

Fig. 3 is a cross-section taken along, line IIIIII on Fig. l. i

Fig. 3a is an exploded perspective view illustrating the details of thejoint between certain elements of the feed water system.

Fig. 4 is a cross-section, drawn on a larger scale, taken along lineIV-IV on Fig. 2.

Fig. 5 is a longitudinal section taken along line v v on Fig. 4.

Fig. 6 is a view analogous to Fig. 1, showing a'modification.

. Fig. 7 is a corresponding horizontalsection analogous to Fig. 2.

Referring to Figs. lto 5, the reference char acter l denotes the bodyportion of a water and lil'le II-II of steam drum of a boiler, whereinin steam-generatingtubes (not shown) open in the zone between ac and bb;cup-shaped end portions'z; 3

are secured to the ends of drum I. Passing through end portion 2 are apair of feed water pipes 4, 5 merging into a common trunk 6' which isthen bifurcated. into a .pair of short sections I, 8 having end flanges9, l0; secured through flanges l I, I2 thereon are a pair of feed waterdischarge pipes I3, id opening towards the bottom of the boiler body todischarge feed water into said boiler body. Squeezed between flanges 9,l l and H3, I2 respectively are a pair of perforated diaphragms such asi I (Fig. 3a) provided for the purpose of building an increased waterpressure upstream.

Passing through the drum l in the neighborhood of the ends thereof arefour water return pipes or downcomers l5, l6, l1, 18; all of them aresimilarly constructed so that one only need be described in detail; pipeIT, for instance, downwardly directed outside the boiler, is connectedto the discharge port He bored in the wall of the boiler or drum I.Instead of permitting the liquid issuing from the boiler to enterdirectly the downcoming pipe I! through port He that would result in theabove-mentioned disadvantages, a suction chamber covering the port Heis. arranged within the boiler upstream with respect to said port.

Inthe embodiment of Figs. 1 to 3, said chamber consists of a plungertube connected to the original discharge port [1e and extending thedowncomer ll within the boiler. Said plunger tube or chamber H forinstance, includes, from the drum wall, a slightly ascending portionIla, then a top part or bend l'lb, forming a steam trap, which mergesinto a downwardly directed u portion llc with a downwardly openingflared end I'Id'. ,Said flared end I'ld is the inlet aperture for theliquid into the suction chamber or tube Hf preceding the originaldischarge port He.

Said. inlet end "id is entirely situated below the. liquid level in theboiler or drum 1, the downcomer I! with the plunger tube I I! acted thenas av syphon. Moreover portion He is directed to the right as seen inplan view, so that said flared end Hd is-located within the end portion3, i. e.

awayfrom bb.

Branching ofi from feed Water pipes l3, M at points upstream withreference to the perforated diaphragms ll, I2 between flanges 9, ll, [0,I2 are four small pipes I9, 20, 2!, 22 which enter chambers I57, I67,l'lf, I8), respectively; pipe 2| for instance includes an end portion21a, located inthe bend Nb of chamber [1 that is to say near the top ofsaid chamber; said portion has a closed end 23 and is formed with adouble row of perforations 24 in its upper zone.

Owing to the foregoing arrangement, relatively cool feed waterisinjected at the high point of pipes such as IT) under a pressure whichmay amount, for instance to some hundreds of grams per sq. cm. and isbuilt up by reason of the provision of perforated diaphragm in feedwater discharge pipes; said relatively cool feed water condenses anysteam carried along with water in return pipes l1. 7

It should be understood that the diaphragm is merely an example of meansto build up an increased pressure in the main feed water pipe, andobviously other known means providing a restriction in said mainpipeupstreamwith respect to its discharge end may likewise be resortedto.

Referring to Figs. 6 and '7, wherein like parts are denoted by likereference characters, a downcoming pipe 25 is shown secured to endportions 2 and a partition 26 supported in the boiler drum l extendsfrom the top thereof to a point substantially above the bottom, formingwith the end portion 2 a trap for steam bubbles and leaving an inletopening 21 which has a sufficiently large cross-section, in such a waythat water passing into the chamber 28 between said partition 26 and endportion 2 moves substantially horizontally. Passing through the wall ofend portion 2 is a rising feed water pipe 29 which opens into ahorizontal tube 30 closed at both ends and perforated in its upperportion. Hanging from end portion 2 above tube 30 is a bell-shapedmember 3| shown as comprised by a semi-cylindrical sheet metal with endcheeks.

Any steam carried along with Water past opening 21 and into the trapbetween the end portion 2 and partition 26 is condensed by relativelycool feed water from tube 30.

While I have described and illustrated specific embodiments which arebelieved to be efficient and reliable, my invention is not restrictedthereto and many modifications may be brought about without departingfrom the spirit of this invention as comprehended by the followingclaims. The term boiler shall be construed broadly as meaning any vesselor reservoir containing a boiling liquid.

What I claim is:

l. The combination of a vapor-and-liquid boiler body for containing aliquid to be heated, an aperture provided in the wall of said boilerbody through which liquid contained in the boiler body may be withdrawn,an external downcomer communicating with said aperture for receivingliquid withdrawn through said aperture, a steam trap chamber formedwithin said boiler body, said chamber having three openings therein, oneof which is said aperture, the second of said openings being adjacent tothe bottom of said boiler body and beneath the level of the liquidcontained in said boiler body, a portion of said chamber extendingupwardly to a point above both said aperture and said second opening,and means extending through said third opening and positioned in thesaid upwardly extending portion of said chamber for cooling the liquidwhich enters said chamber, whereby vapor in the liquid entering saidchamber is condensed and liquid only is withdrawn through said aperture.

2. The combination of a vapor-and-liquid boiler body for containing aliquid to be heated, a feed liquid supply pipe opening into said body,an aperture provided in the wall of said boiler body through whichliquid contained in the boiler body may be withdrawn, an externaldowncomer communicating with said aperture for receiving liquidwithdrawn through said aperture, a steam trap chamber formed within saidboiler body, said chamber having three openings therein, one of which issaid aperture, the second of said openings being adjacent to the bottomof said boiler body and beneath the level of the liquid contained insaid boiler body, a portion of said chamber extending upwardly to apoint above both said aperture and said second opening, and meansextending through said third opening and positioned in the said upwardlyextending portion of said chamber for cooling the liquid which enterssaid chamber, comprising piping extending from said feed liquid supplypipe to the upwardly extending portion of said chamber whereby vapor inthe liquid entering said chamber is condensed and liquid only iswithdrawn through said aperure.

3. The combination of a vapor-and-liquid boiler body for containing aliquid to be heated, a feed liquid supply pipe opening into said boilerbody, an aperture provided in the wall of said boiler body, a downcomerextending thru said aperture into the boiler body and terminatingadjacent to the bottom wall of said boiler body and below said apertureand the level of the liquid contained in said boiler body, the portionof said downcomer within said boiler body having an intermediate sectionpositioned at a point above said aperture to form a vapor trap, andpiping extending from said feed liquid supply pipe to said intermediatesection, whereby vapor in the heated liquid passing through saidintermediate section is condensed by the cooler liquid supply introducedinto said intermediate section through said last named piping.

4. The combination of a Vapor-and-liquid boiler body for containing aliquid to be heated, said boiler body consisting of a body portion andtwo end portions, an aperture provided in one of said end portionstoward the bottom thereof through which liquid contained in said boilerbody may be withdrawn therefrom, a downcomer communicating With saidaperture to receive the liquid withdrawn therethrough, a partitionwithin said boiler body separating the upper sections of said one endportion and said body portion to form a vapor trap in said one endportion, the lower sections of said one end portion and said bodyportion being in communication with one another through an openingprovided in the lower section of said partition beneath the level of theREFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 565,986 Hogan Aug. 18, 1896985,834 Parker Mar. 7, 1911 2,169,935 Vorkauf Aug. 15, 1939 FOREGNPATENTS Number Country Date 130,736 Germany May 16, 1902 257,100 GermanyFeb. 27, 1913 OTHER REFERENCES Page 197 of Power, published Mar. 4,1919, vol. 49, No. 9.

